With a Bang: The Science of Fireworks

You've probably set off a firework or two in your time, but do you know how fireworks work? This Fourth of July, we'll burn our way through a few common examples of every stripe, flash, and boom. You've seen the lights. Now know the science.

Snap 'n' Pops

Snap 'n' Pops

These little balls of paper so harmless they're legal year-round. But what's going on under there?

Silver fulminate is an incredibly reactive explosive. The slightest impact or heat sets it off. Because of that instability, it's rarely used as a commercial explosive compound. You don't want to set off a stick of dynamite by bumping it the wrong way.

There is one use for it, though. You'll find about 80 micrograms of it in every snap 'n' pop, along with a bunch of tiny bits of gravel. The gravel gives the silver fulminate the friction it needs to ignite.

Sparklers

Sparklers

Sparklers are a familiar sight on Independence Day. Essentially, they're made from iron filings and aluminum powder stuck to a metal rod, with a starchy water solution that acts as a glue. Once the sparkler is lit, the metals rapidly oxidize with the help of an oxidizing agent, barium nitrate, which is how they give off sparks. The sparkler burns out when it reaches the end of its fuel.